The present invention relates to a switching device for switch tongues the tongues tip of which lies on a roller plan of a slide chair.
In the known switching devices for switch tongues, the movable, i.e., horizontal pivotal regions of the switch tongues slide on slide surfaces of a slide chair. For achieving small switching forces, the slide surfaces should be greased at a certain intervals in order to obtain an operability of switching of the tongues. At high temperatures, e.g., in summer or as a result of point heating in winter, the grease resinifies often relatively very rapidly and dries up, so that the switch tongues can be switched only with a great difficulty or cannot be switched at all. If the switching device becomes inoperable, its operation should be interrupted as long as necessary for eliminating the malfunction, primarily, by greasing. During rain, e.g., the rain water often carries the grease away into a track bottom ballast which then penetrates into ground waters, which leads to pollution of the drinking water. This is non-tenable.
In order to prevent both an interruption of the operation and the ecological pollution of the ground water, it was suggested to arrange the movable regions of switch tongues on roller or ball supports and thus provide, on one hand, a rolling friction and, on the other hand, to eliminate the detrimental greasing.
In the known point-operating devices, primarily, roller supports, which have one or more rollers, are used. The roller supports are secured in a space between the cross-ties to a base of the stock rail, or are integrated into a plate of the slide chair secured to a cross-tie top. The rollers themselves can be fixedly or resiliently arranged, e.g., in an attachment frame.
The support plane of the fixedly arranged rollers, which is engaged by the bearing surface of the switching tongue heel, lies, for the most part, from about 1 to 2 mm above the slide surface of the slide chair. The correct level or elevation of the rollers is achieved, in accordance with the position of the rollers in the switching device, by insertion of sheet metal spacers. Either between the base of the stock rail and the attachment region of the roller support or between the cross-tie top and the base frame. Thereby, the rollers are arranged closed to the carrier. Despite this very laborious and relatively large time-consuming adaptation work, often other drawbacks emerge. Namely, the slide surface and the support of the base of the stock rail do not lie any more parallel to the cross-tie top, which lead to tilting of the rolling surface of the stock rail in the transverse direction.
Because of a very small clearance between the switch tongue and the slide surface of the slide chair and a small horizontal displacement of the tongue heel in the region of the switch tonguexe2x80x94support point, the sliding surface there cannot be lubricated. Therefore, they are provided with, e.g., a molybdenum or similar cover layer. If this covering corrodes or wears off, the slide surfaces, which are formed as separate plates, should be replaced, which is associated with high costs.
With the resiliently supported rollers, the switch tongue lies on the rollers not only during switching but also during its travel. This is a serious drawback because a smaller or larger clearance is created between the slide surface and the lifted switch tongue which may amount up to 5 mm. During the travel, because of the speed, the generated smaller or greater kinematic forces cause a corresponding impact of the tongue heel on the slide surface of the slide chair which becomes damaged as a result of plastic deformation. The plastic deformation of the bearing slide surface of the slide chair often leads to breaking of the tongue.
The object of the present invention is to provide switch device of the above-described type without the above-listed drawbacks, and with which a particularly easy tongue switching can be effected.
This object is achieved, according to the invention, by positioning the front roller of the roller pair lower than the real roller. The front roller, which is understood to be the roller on which the switch tongue runs-on first during its horizontal adjustment, is so supported that its apex is only slightly elevated above the slide surface of the slide chair. This enables an easy sliding of the tongue heel over the front roller, on one hand, and on the other hand, the horizontal force, which acts on the front roller during the run-on of the tongue heel on the front roller, is reduced by about 50% in comparison with the conventional devices when both rollers lie on the same level. Further, the front roller favorably influences a gentle sliding of the tongue heel onto the higher positioned rear roller. An easy, stepless sliding of the tongue heel on the rollers is improved by forming a chamfer in the region of the tongue base which is closest to the front roller.
According to a further embodiment of the invention, a roller is also provided in the region of the tongue heel. According to the invention, the height level of the tongue heel roller differs from those of the front roller pair. Thereby, it is possible to reduce the deflection of the switch tongue which bends vertically similar to a cubic parabola between the tongue tip and the tongue heel so that no vertical spacing is possible between the bearing surface of the tongue base and the support surface of the slide chair. The smaller deflection of the switch tongue prevents the tongue heel from engaging the slide surface in the region of the support point. Thereby fewer sliding surfaces require a cover layer in the region of the support point, on one hand, and on the other hand, the switch tongue can be switched more easily as a result of being supported with sliding friction in the region of the support point of the tongue heel.
According to an advantageous embodiment of the present invention, at least one roller is supported on an eccentric axle, and actually in each case, the front roller of the roller pair to provide for positioning of the front roller at a lower level than the rear roller in order to insure a more easy sliding onto the second, rear roller. The eccentric support with an eccentric axis provides for an easy and stepless height adjustment of the front roller and its retaining in the adjusted position.
When, advantageously, the roller associated with tongue heel has an eccentric axle support, it is possible to lift the tongue heel, if necessary, only about the fractured portion by mm, so that it does not lie on the slide surface in the support region of the tongue heel.
According to a further development of the invention, the roller axle support has a stop. The stop limits the highest and the lowest positions of the roller, while it lies on the corresponding bearing surfaces of the slide chair or the fixing frame.
In accordance with a further embodiment of the invention, the rollers are arranged in a linearly movable frame. The displacement of the fixing frame, which is integrated into the slide chair, enables, during the adjustment of the roller pair, to displace the front roller as close as possible to the tongue heel, so that a rolling movement begins, during the switching of the switch tongue, as early as possible.